The present disclosure relates generally to seismic imaging. More specifically, the present disclosure relates to method, software, and systems for imaging seismic data acquired in a wide azimuth configuration, such as wide azimuth marine seismic data, wide azimuth land seismic data, wide azimuth OBS data (ocean bottom seismometer node), OBC data (ocean bottom cable data), and VSP/vertical cable seismic surveys.
Subsalt seismic image quality in the deep water Gulf of Mexico is often very poor when conventional narrow azimuth 3D data sets are used, even with the most advanced processing and imaging methods as discussed in Regone, C. 2006, A modeling approach to wide azimuth survey design for subsalt imaging: SEG Summer Research Workshop, Snowbird, Utah. This is due, at least in part, to the narrow azimuth acquisition geometry typical of towed streamer 3D seismic surveys. As a result, the oil and gas industry is moving towards acquiring seismic data that has better azimuth coverage, and, presumably, better illumination. These types of seismic acquisitions can be designed to make wave equation based shot record migrations very efficient as described in Howard, M. 2004, Rich Azimuth Marine Acquisition, EAGE Research Workshop, Advances in Seismic Acquisition Technology.
Acquiring wide azimuth seismic data is expensive when compared to conventional seismic data acquisition, and presents significant challenges in the subsequent processing, imaging, and interpretation of the data due to the shear size and high dimensionality of the data volume. For example, most existing tomographic velocity updating methods are designed with narrow azimuth assumptions and with offset image gathers as input. The wave equation based shot record migrations will not be able to produce the kind of gather output required by most velocity analysis and updating software. Current practice is to resort to conventional Kirchhoff prestack depth migration with a subset of the data (based on the azimuth range) to produce migrated gathers for 3D velocity model building as described in Ladart, S. et al., 2006, Wide Azimuth Tomography—is it necessary? SEG Technical Program Expanded Abstract. As a result, the accuracy of 3D subsurface velocity models may be greatly compromised.